US2626551A - Cultivator - Google Patents

Description

Jan. 27; 1953 J. H. STARR 2,626,551

CULTIVATOR Filed Nov. 30. 1946 4 Sheets-Sheet l INVENTOR JOHN H. STARR J. H. STARR Jan. 27, 1953 CULTIVATOR 4 Sheets-Sheet 3 Filed Nov. so, 1946 I ENTOR JOHN H. STARR J. H. STARR Jan. 27, 1953 CULTIVATOR 4 Sheets-Sheet 4 Filed NOV. 50, 1946 I N VEN TOR I JOHN H. s

Patented Jan. 27, 1953 UNITED STATES PATENT OFFICE ,Deere YanBrunt Wisconsin Company, a corporation of Application-November 30, I946; SerialzNo. 71335340 :17. Claims. 1

The present invention irelates :generally -i.to agricultural implements and= moreiparticularly:to implements that. are: adapted to :be mountedroma "tractor to bepropelledzthereby and controlled by the. operator on thetractor.

lTheobject and. general nature of the present invention is .the zprovision ."of :an :agricultural :implement having new and improved :means for hitching the implement to .-.the .tlactorzso as x150 maintain substantially a: constant ;depth:of operation without the use of gauge wheels .aoriithe like. f'Morexparticularly, it is a ieature-nf'ithis invention to provide: a field -cultivator hitched to the.tractor-and supported thereby in such a way as to maintain a substantially constant depth of operation, which may lbe controlled as desired, even when the field is uneven or rolling and whereby the depthof operation is substantially maintained :even though the-tractor maytipupw'ardly or downwardly when passing over-uneven ground.

Another important feature of the present invention is the provision ci a tractor-propelled *implement wherein the draft pull is, in effect, balanced against the Weight of the implement and/or the'weightand suckof the groundworking tools and in which verticalmovemenvof the implement relative to the ttractor "is accommodated without having any substantial effect on --the depth of tools during operation. Further, it is -a *feature of this invention "to 'provide an implement of this kind particularly adapted for 'use with tractors having a powerlift unit and wherein the connections aresu-ch-that operation of the power lift unit serves *to control" the depth of operation, which is substantially maintained, and. may also beutilized toraise' the "tools into their transport positiongeasily-and-rapidly.

Theseand other objectsandgadvantages oftthe *present invention will be Lapparent 'to 'those skilled-in the-art after a consideration-of-the following-detailed descri-ption, taken in conjunction with the'accomp anying' drawings.

Inthe drawings:

Figure-1 is a side=view-of the-rearportion ofa tractor mounted field -culti-vator in which the *principles of the --present invention have *been incorporated.

-Figure 2 is *a similar Side view showing the .front portion --of the tractor mounted fiel'd -cultivator shown iii-Figured.

Figure'3 is I an enlarged*detailviewtaken generally-along the line3"3of Figure 1.

:Eigure 4 is :a wiew taken generally alongthe plinei'llwttofxfiigurel.

:Figure :5 is {a view .taken' enerally along the line-5-5 of Fi ural Figures 6 and .7 are fragmentary side views illustrating the manner in which the :cultivator ,of the present invention -adantsv itself to uneven .terrain while'maintaining substantially constant depth of operation.

Figure 8 .is a =.view {similar to Figures G-and fl, rshowing'the cultivator in its1raised; position.

Figures 9 land :10 Sh0W a modified/form iQf the invention.

Referring jznow .to the drawin s, particularly Figures .21 and 2, :the tractor @on which the implement of the;present. inventiomisimounted is indicated .in its entirety: by the;ref ,ereno e numeral 1| andsofar as the: present inventionis. concerned :is'largely conventional. 'Ihegtractor ql iis prcvidesi .with a frame] .containingor supporting znower .plant, suchasa gasolinerengine, andisrcarli-ifidaon front wheels (not .shown) and la pair of .relatively widelyspacedrear traction Whee1s-.4.;fixed to axle shafts 5 that are journaledfon rotationin .azrear axlestructurefi. .The. tractorl is also-sprozvided 'With a power lift unit :1 which includes suitable operating ;-1 mechanism, including :a valve operating lever 8, and a .rockshaft :onwhic'h apower lift :arms ill :are :securedrior .:.m.ovemen betweenalowered positiomandnnlupper or raised position.

The implementchosemto: illustrate itheipresent invention is shown as. a.-spring.toothcfield-nuiti- .vator indicatedinits entirety .byrreference numeralzil. .flhe cultivator zwiincorporates. :.a frame .21 which includes bright and :left handngenerahy longitudinally extending f-rame bars i2 2, ipreferablyintheform of angles,.therearaends of=.which .are turned upwardly, z-iorming upwardly and :rearwardly angled sections r23. -..On vthe :latter sectionsis fixed .a .pairuof :transverse -.angles r214 and 25, which together with suitable :crossibars, .form means for-receiving .a.p1urality.:of .aJdraQbars 21 which :are -:pivoted to 1 the :front angle 1-25.:and which carry :rear cultivator rteeth Z8. 'Llhe .L drag bars are normally held .in ;:operating:positioniby a plurality ofzcompression springs J31 disposed -.above:pressure rods 32 that-are pivotediat their lower and rear ends to the associated. dragbars .and which at their upper ends pass through brackets 33 against which the upper ends-ofithe springs 3| bear, as thusishownin Figure 31. lock nut 34 vor the like .limits the downward movement of each rod 32 relative :to ztheias- 'sociated bracket 33. fIl e :forward ends :of athe Iframe 'bars 22 are connected together by-suitable crosslbraces :(not shown) and.:are:connected tractor.

tool frame 2| 'in the journal box IE.

by strap members 36 to a hitch structure 3'! which comprises generally fore and aft swinging links 38 pivotally connected at their upper ends, as at 39, to an adjacent portion of the tractor frame and at their lower ends, as at 4|, the links 38 are pivoted to the strap members 36. This structure permits the implement frame 2| to shift generally fore and aft, but the front end is held against any substantial amount of generally vertical movement. A draft bracket 50 is fixed at each side of the tractor, preferably to the outer end portion of the associated rear axle structure and preferably takes the form of an angle 5I secured, as by studs 52, to the axle housing. The angle 5| extends downwardly and its lower end carries an upwardly and rearwardly extending bracing strut 54, the upper end of which is provided with an adjusting set screw 55 that is adapted to bear against a bar 56 that is bolted, at 51, to the rear side of the axle housing 6. A generally horizontally extending draft connection 60 is provided and is preferably in the form of a chain BI which at its forward end is connected by a link 62 (Figure 3) to a bar 64 which at its forward end carries a stud 65 on which a roller 68 is journaled. The roller 66 bears against the forward edge 61 of the angle 5| and thereby provides for generally vertical movement of the draft connection 60 relative to the tractor while receiving draft therefrom. The lower portion 67a of the edge 6'! slants rearwardly, as best shown in Figure '2, for a purpose which will be explained later. There is a draft bracket structure 50, as described above, fixed at each side of the tractor I and there are two draft connections 58, one at each side of the tractor connected to the draft brackets 50 for vertical movement relative thereto. Each draft bracket angle 5| is provided with a vertical strap member 68 that embraces the link 64 for holding the latter and the roller 66 in position while accommodating vertical movement relative to the The strap member 68 has its upper and lower ends 69 turned laterally and secured, as

by welding, to the outer flange of the associated draft bracket angle 51.

The rear end of each draft connection 60 is received by and connected to a cam member 75 that is mounted for rocking movement on the generally transverse axis by any suitable means,

ated frame angle or frame bar 22. Each of the cam members includes an outer cam section 8i and an inner cam section 82 rigidly fastened together as by a cross shaft 83 which is received The cam section 8| is preferably formed as an elongated member having a grooved periphery, as indicated at 85, and .a bifurcated extension 86 which is apertured to receive a pin 8'! that connects the rearmost link ofthe chain 6| to the cam section BI, with the chain received in the groove 85 of the cam section 8|. The outer end of the shaft 33 is drilled and tapped to receive a cap screw 89, or other suitable means, for fastening the cam section 8| rigidly to the shaft 83. Preferably, the outer end of the shaft is flattened or otherwise formed to definitely locate the cam section 8|, so far as its angular position is concerned, relative to the inner cam section 82.

A lifting connection, indicated in its entirety by thereference numeral 90, extends from each of the inner cam sections 82 upwardly to a point for rocking movement about a on the tractor. As best shown in Figures 1 and 4, each lifting connection includes the chain 9| or other flexible elements, the lower end of which is received in the grooved portion 93 of the inner cam section 82, the lower end of the chain 9| being connected, as by a pin or bolt 94, to the member 82. The chain SI extends upwardly from the cam section 82 over the roller 95 that is journaled for rotation on a shaft 96 that is carried by a bracket 91 bolted to the rear side of the associated portion of the tractor rear axle 6. From the roller 95, the chain 9i extends upwardly and rearwardly over a sheave 91 that is carried at the outer end of the power lift arm I I at that side of the tractor, and from the sheave 91' the chain 9| extends downwardly to a threaded hook bolt 98 that is adjustably connected into a swivel member 99. The latter member has a lower bifurcated section which is apertured to receive a pin H32 on which a roller I03 is mounted. The roller Hi3 bears against the lower edge of the central portion I04 of an elongated bracket I65 that is secured to the associated frame angle 22, preferably by a bolt I06 and the bolt TI that connects the rear portion of the journal box I6 to the frame angle 22. As best shown in Figure 1, the inner cam section 82 is approximately semi-circular in configuration and bears a given angular relationship with respect to the associated outer cam section 8|.. The bracket 97 is secured, as by welding, to the bar 55 that is bolted to the rear axle housing mentioned above. Mounted on each of the brackets 9'5, preferably the upper portion thereof, is a notched sector I I5, the sector H5 being rigid with respect to the bracket 91, and a hand lever H6 is pivoted, as at ill, to the bracket 97 and includes spring biased detent mechanism H3 which operates along the sector I I5 the notches of which are tapered so that the detent slides out when the lever H6 is pulled in either direction. The hand lever I I6 carries a stud II9 which cooperates with a notched portion I2I on an extension I22 of the associated power lift arm II. The extension I22 is shaped so that swinging the hand lever [I6 positions the stud II9 so as to serve as a stop for locking the associated power lift arm II against downward movement, whereby, according to the position of the hand lever I iii, the power lift arm is held in different or various lowered positions,

as desired, but when the valve lever B of the .75 in a clockwise direction, as viewed in Figure 1.

This rotation is opposed by the lifting connections 90. It will be seen that the lower end of each of the chains 9| is connected to the inner cam section 82 and is trained over the forward portion of the section 82, as shownin Figure 1, whereby any clockwise rotation of the cam member I5 acts through the lifting connection to raise the rear end of the frame 2|, it being rememberedthat the power lift arms II are locked by the hand lever H6 in the positions shown.

Thus, the draft pull is balanced against the weight of the implement frame and the suction of the't001s-28. Hence, if there shouldoccur an increase in the draft pull, transmitted from the tractorto the implement through'the chains 61 trained over the outer cam sections 81, the cam members '15 are rotated in-a-clockwise direction, as viewed in Figure 1, and-since the lower ends of the lifting chains 9-1 are trained over the "inner cam sections82 onthe for-ward side thereof such clockwise rotation of the cam members 15 acts-to shorten the effective 'lengthof the lifting chains 9| and thus'raisesthe tool -'into a'more shallow depth of operation. 'If,-on the otherfhand, :the draft -pul1 transmitted to the draft-connections 6| should decrease, the suction of the 'tools and the weight of the frame act through the lifting chains 9i to cause the cam members '15 to "be rotated in a counterclockwise direction -so as to permit the frame and'tools to take 'alower position-relative to the tractor. The cam=sections 8i and-82 of each cam member 15 are so angularly related that the draft'pullis always balanced againstthe weight of the implement and suction of the tools, whereby thetools under normal conditions'maintaina substantially constant depth of operation, any displacement therefrom resultingina change in-the'position of thecam members 15 which, .in turn, sets up restoring forces. The position of'the parts shown in Figure 1 represents a normaloperating position, where the effective moment arm-of the draft chains 6! is relatively great while the effective moment arm of the lifting chains 9! is relatively small. Itwill be seen from Figure l-that if the draft pull should increase the clockwise-swinging of theoutercam sections 8| would result in shortening the moment arm of the draft chains-6'! while, at the same time, increasing theeffective moment arms of thelifting chains 9 I thereby bringing .the cam members 15 into positions where thesuction of the toolsand the weight of thesamebecome sufiicient to oppose-any further tendency of the draftpulL -transmitted to the lifting chainsfil, to rotate the cam members 15, whereby the parts are brought to equilibrium.

The arrangement just described is particularly advantageous in that it will be-noted that-the rear end of the tool frame'is not rigidly tiedto the rear end of'thetracton'and hence the front end I of the tractor may oscillate upwardly or downwardlywithouthavingany-greateffect upon the position 'of the implement relative to the ground or the depth of operation. That is, ifthe front end of the tractor *shoulddropinto adepression, the power lift arms I 'I are raised'since the rear axle of the tractor becomes the pivot point, and this tends to raise;the rear endof the tool frame and pull the =toolsoutof the ground or at'least into a position of moreshallow operation. The resultant decrease inthe draft pull transmitted through the chains 6 i would permit the weight of the frameand thesuction ofthe tools to cause the latter to move downwardly, relative to the tractor, 'so as to accommodate for the lower position-of the front -end of the tool frame, thus securing a substantially constant depth-of operation. Likewise, if the front end of the "tractor should pass -over a ridge, which would elevate the front-'endof the-tool-frame and ordinarily tend to permit the toolsto move into -a--'deeper position of operation, the resultingincreasein-the-draft would momentarily cause the cam sections 15 to-be rotated -in -'a-" clockwise di- 'rection whichwould wind-upon the lifting chains 9 I and thus tend" to lift the :rear end of ithei-tool frame into a more shallow position :of operation. Thus, the implement of the present invention operates at substantially aconstant depth of :operation even over rough or uneven terrain. When desiredgthe power lift arms mayfbe raised or lowered from the position shown inFigure vl in order to change the normal positionof equilibrium relative to the tractor .and thus, in effect, change the normal depth of operation-of the tools. Also, whenit'is desired torraise the tools out of the. ground, asfor transport, the'powerlift valve 8 is operated toraise the .arms ll .into theirfully .raised position. Thisinitially pulls upwardly on both. sections 'of the chain 9 l, raisingthe rear end of theframe, but in orderzto provide a more rapid lift, I secure'an abutmentror stop t25con the forward portion ofthelifting chain, a short distance above the "associatedscam section 82. Each "abutment :stop I25 is of :suflilcientrsize so that when it is brought upwardly into contact withthe associated roller 95, it also engages the associated bracket 91. and so prevents further upward movement of the forward section of the chain 9|. Hence, subse.quent movement of the power liftarms ll into their fully raised..position acts through therear sections .of the chain 9| to rapidlyraise .thetools .into their transport position.

The position of the'parts shown in Figure l is that :for shallow cultivation, and if deeper .cultivation is desired, the hand levers H6 are operated to permit the power lift arms H tolower. Not only does this provide for lowering of the entire draft responsive linkage, the roller 66 shifting downwardly along the frontedges-Bl of the draftangles 5!, but also, and more importantly, the lowering or raising of the power'lift arms ll causesthe cam members 151:0 take different positions to accommodate the required change in the relation of the lift arm to the draft arm for deeper or shallower work. For various cultivating depths the draft chains Bl are always operating in a generally horizontal plane. However,;for the. deeper positions, the rollers 96 engage the rearwardly inclined edges E'la. This serves to prevent undesirable upward shifting of the rollers '86 and thereby secures better stability when operating at the deeper positions where, because of the tooth depth, small differences in theground resistance against the tools 28 would change the draft forces rapidly. -For generally normal penetration under average conditions the draft cams l5 are rotated forwardly about 45 from their positions shown in Figure 1.

"Figured shows the position of the equalizing cams and associated parts when the cultivator traverses a ditchorlow place, which is generally about the same as when the front wheels of the tractor drop into a low place or ditch. ;In this position of the implement, the. cultivator has been shifted several inches forwardly relativeito the tractorv and the equalizing cams have been-rotated in a counterclockwise direction (Figure 1 Since now the moment arm of the lifting chain'is appreciably greater than the moment arm of the draft chain, the tendency is for the tools to move down- .wardlly relative to the tractorand so maintain .a .ridge 101' hump in the soil. #As the'rear -end of.'the..cultivator moves upwardly relative ito ithe tractor the cultivator frame shifts generally rearwardly, the cam sections moving into a position where the moment arm of the lifting chain is increased which effectively balances the draft pull.

In general, the deeper the operating depth, the lower will be the points at which the rollers 66 normally engage the draft angles If, however, the cultivator should be set deep enough to stall the tractor and cause the Wheels to spin and sink into the ground, the resultant lowering of the rear end of the tractor relative to the tool frame causes the front portion of the lifting chain 9I to go slack, approximately twice the rate of lowering of the tractor relative to the tool frame. This permits the tractor to move forward a short distance until the clockwise rotation of the cam members takes up the slack. Under these conditions, as the tractor moves forwardly the connection point 81 on each cam member swings around into an upper position, beyond that shown in Figure '7, for example, momentarily increasing the moment arm of the draft connection so that as the tractor reaches the end of the slack in the lifting chain the cultivator is lifted out of its stalled position. Also, under these conditions where the wheels tend to mire into the ground, the rollers 66 move upwardly along the front edges of the draft angles 5I, thus preventing the draft connection from pulling the cultivator down into the ground again and stalling the tractor.

Figures 9 and 10 illustrate a modified form of the present invention, somewhat simpler than the form of the invention described above. Referring now more particularly to Figure 9, the cultivator and frame are substantially the same as described above and hence have been indicated by the same reference numerals. In one particular, however, the cultivator frame 2| differs slightly from the construction shown in Figure 1. As best shown in Figure 10 the vertical flange of each frame bar 22 is apertured and a short section of reenforcing channel I3I is welded to each frame bar 22, the vertical flange of the reenforcing section I3I being apertured to receive the shaft 83 of the cam member I5. In the form of the invention shown in Figures 9 and 10, the cam members I5 are of substantially the same construction and configuration as shown in Figures 1 et seq., and hence the same reference numerals have been used. In the form of the invention shown in Figures 9 and 10, a lift chain I 33 is connected at its lower end, as at 94, to the lift cam section 62. The chain I33 extends upwardly, passing over a roller I35 carried on the associated power lift arm II, and from the roller I35 the chain I33 extends forwardly to a hook member I36 fastened to the rear axle housing 6 at that side of the tractor. A draft chain MI is connected at its rear end, as at 81, to the draft cam section 8! of the cam member I5, the chain I4I extending forwardly and at its forward end being connected to a generally longitudinally extending elongated draft link I42, the forward end of which is connected by a swivel I43 to the lower end of a draft bracket or plate I44 bolted to the side of the tractor, as by a bolt It? and the bolt I39 that pivotally connects the upper end of the link 38 to the tractor.

In this form of the invention the cultivator is quite easy to assemble and may quickly and easily be attached to or removed from the tractor. The relatively long draft connection I4I, I42 between each draft arm or cam 8| and the forward portion of the tractor provides for a substantially horizontally applied draft pull in theseveral positions of the cultivator relative to the tractor, and the operation of the implement shown in Figures 9 and 10 is substantially the same in principle as the implement shown in Figures l8 and described above.

While I have shown and described above the preferred structure in which the principles of the present invention have been incorporated, it is to be understood that my invention is not to be limited to the particular details shown and described above, but that, in fact, Widely different means may be employed in the practice of the broader aspects of my invention.

What I claim, therefore, and desire to secure by Letters Patent is:

1. An agricultural implement adapted to be connected with a tractor to be propelled thereby, comprising a tool frame, ground working tool means having suction carried by the rear portion of said frame, means for connecting the forward portion of the frame with the tractor for generally free fore and aft movement relative to the tractor, a generally forwardly extending draft connection, means for connecting the forward end of said draft connection to the tractor for generally vertical movement relative thereto, a generally upwardly extending lifting connection adapted to be connected at its upper end to the tractor, and shiftable motion transmitting means connected with the tool frame and said draft and the rear end of said lifting connection whereby the draft pull transmitted by said draft connection is directed differentially against said tool frame to propel the same and against said lifting connection to oppose the weight of said frame and the suction of said tool means.

2. An agricultural implement adapted to be connected with a tractor to be propelled thereby, comprising a tool frame, ground working tool means having suction carried by the rear portion of said frame, means for connecting the forward portion of the frame with the tractor for generally free fore and aft movement relative to the tractor, a generally forwardly extending draft connection adapted to be connected at its forward end to the tractor, a generally upwardly extending lifting connection, shiftable motion transmitting means movably mounted on said frame, means for connecting one end of said lifting connection with said motion transmitting means, means for connecting the other end of said lifting connection with said tool frame, means for connecting the intermediate portion of said lifting connection with the tractor, and means for connecting the rear end of said draft connection to said motion transmitting means, whereby the draft pull transmitted by said draft connection is directed differentially against said tool frame to propel the same and against said lifting connection to oppose the weight of said frame and the suction of said tool means.

3. A tractor propelled implement adapted to be attached to a tractor to be propelled thereby, comprising a frame adapted to extend generally longitudinally of the tractor, ground working tools carried by the rear portion of said frame generally rearwardly of the tractor, generally fore and aft shiftable means adapted to connect the forward end of the frame to the tractor and prevent generally vertical movement of the front end of said frame relative to the tractor, a draft connection between said frame and the tractor, and means connected with the draft connection and thereby responsive to the amount of draft pull for. raising the-rear portion.of. the frame relativetothe tractor, said last mentionedimeans comprising; a, sheave-like member, pivotally mountedon said frame and havingtlwoigenerally non-circular sections connected to rotate to- .gether, one receiving. said draft connection, and

be attached to a tractor, to be propelledthereby, comprising a frame adapted to extendlgenerally longitudinally of the tractor, ground work- ,ing tools carriedby therear portion of. saidframe generally rearwardly of, the tractor, generally fore and aft shiftable meansv adapted, to connect theforwardend of the frame to the tractor and prevent generally Vertical'movement of the front end' of said frame relative to the tractor, a draft connection between the inter-mediate portion of said frame and the tractor and including a horizontally disposed part adapted to beconnected at its forward end with the tractor for vertical shifting movement relative to the tractor, means connecting the rear end. of said part with the frame, said latter means including a member movable relative to the frame in response to the amount of draft pull exerted between the tractor and said .frame, and means connecting said member with the tractor at a, point above said frame whereby movement of said member serves to raise; and lower said frame, said part remaining generally horizontal indifferentvertical positions of said frame relative to the tractor.

5. An agricultural implement adapted to be connected to a tractor to be propelled thereby, comprising a tool frame adapted to extend longitudinally of the tractor. means for connecting the front end of said tool frame with a forward portion of the tractor for generally free fore and aft movement relative thereto, ground working tool means having suction carried by the rear portion of said tool frame, a generally horizontally extending draft connection adapted to be connected at its forward end with the tractor to receive draft therefrom, a cam member rockably connected with said tool frame and including a pair of cam sections, one receiving the rear portion of said draft connection, and a lifting connection received by the other cam section, said lifting connection having a flexible member fixed at one end to said other cam section and at its other end to said tool frame, the intermediate portion of said lifting connection being adapted to be connected with the tractor, said cam sections being so angularly related that the draft pull transmitted through said draft connection tends to rotate said cam member in one direction while the weight of the tool frame and the suction of said tools tend to rotate said cam member in the other direction, whereby the draft pull is balanced against the suction of the tools and the weight of the frame so as to maintain.

substantially constant depth of operation.

6. A field cultivator adapted to be mounted on a tractor, said cultivator comprising a frame adapted to be disposed generally longitudinally of the tractor, a flexible element connected at one end to the tool frame at one side thereof and upwardly to a point of connection with the tractor and then downwardly toward said frame, a double cam member having a first cam section, receiving the other end of the associated flexible element, and a second cam section, and a .flexible draft -element"jconnected at its rear; end

to said second cam, section and adapted to be connected at its forward end to the tractor in draft transmitting relation, the angular relation between the cam sections of. said dobule cam member being such that the weight of said'frame tendsto rotatesaid cam member in one direction andthe draft pull transmittedby saiddraft element tends to rotate said cam member in the other direction.

7. A field cultivator. comprising; amobile sup port, atool'frame extending generally longitudinally thereof, hitch means. connecting the, for,- ward endofsaid' frame with said support for generally fore and aft movement relative thereto, a pair of interconnectedicam members mount'edfor rocking movement, on,the generally. rearward portion ofsaidframe, a. generally longitudinally extending draft element. connected. between. one ofsaid cam. members andfsaid. support so as to receive draft therefrom,. and a; generally upwardly extending lifting elementconnected. be-

tween the other cam,member and said support,

said cam members being so. angularly related that in operation the draft pull is counterbalanced against theeffective. weight of said frame and tool means and any tendency for the tool means to run into. the ground, whereby substantially constant depth of. operation is secured...

8. A field. cultivator adapted to be connecte to a, mobile support to be propelled thereby, comprising a tool frame, hitch means adapted.- to connect the forwardend-of said frame-with said support for generally. forev and aft; movement relative thereto, a pair of interconnected cam members mounted for rocking movement on the generally rearward portion of said frame, a generall longitudinally extending draft element adapted to be connected between one of said cam members and said support so as to receive draft therefrom, and a generally upwardly extending lifting element adapted to be connected between the other cam member and said support, said cam members being so angularly related that in operation the draft pull is counterbalanced against the effective weight of said frame and tool means and any tendency for the tool means to run into the ground, whereby substantially constant depth of operation is secured.

9. An agricultural machine adapted to be connected with a tractor, said implement comprising a tool frame, tool means carried thereby, a generally horizontally extending draft connection adapted to be connected at its forward end with the tractor, a generally upwardly extending lifting connection, motion transmitting means carried by the tool frame and receiving the rear end of said draft connection and the lower end of said lifting connection whereby the weight of the frame and the suction of the tool means is balanced against the draft pull so as to maintain substantially constant depth of operation, said lifting connection comprising a flexible element, a sheave carried by the tractor and receiving said lifting connection, one end of the latter being connected to the above mentioned motion transmitting means and the other end being connected with said tool frame, means for raising said sheave, and stop means acting between the portion of said lifting connection at one side of the sheave and the tractor, whereby movement of said sheave in an upward direction raises said tool frame at a rate of movement that is greater than the vertical movement of said sheave.

10'. The invention set forth in claim '7, further characterized by said mobile support having an upwardly swingable arm carrying a sheave, and said upwardly extending lifting elements being trained over said sheave and extending downwardly to a point of anchorage on said tool frame.

11. The invention set forth in claim 7, further characterized by said cam members being grooved and said draft and lifting elements being flexible and having portions disposed in said grooves and connected with said cam members.

12. The invention set forth in claim 11, further characterized by the grooved portions of said cam members being so shaped that when said members are rocked in one direction or the other from a generally central position, the effective moment arm of one of said elements isincreased while the effective moment arm of the other element is decreased.

13. The invention set forth in claim '7, further I characterized by a sheave adapted to be carried by said mobile support and receiving the upper portion of said lifting element, and means for connecting the upper end of said element with said support.

14. The invention set forth in claim 7, further characterized by the forward portion of said draft element extending alongside the tool frame, and means for connecting the forward end of said draft element with the forward portion of said mobile support.

15. The invention set forth in claim 7, further characterized by said hitch means comprising a swingable link adapted to be pivotally connected with said support and pivotally connected to the forward portion of said tool frame. and means for connecting the forward end of said draft element with said mobile support at a point adjacent said swinging link.

16. The invention set forth in claim 7, further characterized by means for connecting the forward end of said draft element to the forward portion of said mobile support, and means for adjustably connecting the upper portion of said lifting element with said mobile support.

17. The invention set forth in claim 7, further characterized by a sheave adapted to be connected with said mobile support and receiving the upper portion of said lifting element, the latter being flexible and extending forwardly from said sheave, and means for connecting the forward end of said lifting element to said mobile support.

JOHN H. STARRJ REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,354,250 Evans July 25, 1944 2,366,155 Silver Jan. 2, 1945 2,436,155 Silver l Feb. 17, 1948 2,462,641 Hyland Feb. 22, 1949 FOREIGN PATENTS Number Country Date 338,256 Germany -L June 15, 1921

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